JPH10223930A - Semiconductor light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make sure the electrical connections between p- and n-side electrodes on the same surface side of a laminated semiconductor section formed on a substrate to form a light emitting layer and other leads by forming the p- and n-side electrodes to substantially equal heights. SOLUTION: After a laminated semiconductor section 10 is formed as a light emitting layer on a single-crystal substrate 1 by successively laminating semiconductor layers 3-5 upon another, a p-side electrode 8 is formed in a state where the electrode 8 is electrically connected to a p-type layer 4 on the surface side of the laminated section 10. Then an n-side electrode 9 is formed in a state where the electrode 9 is electrically connected to an n-type layer 3 exposed by removing part of the laminated section 10. At the time of forming the electrode 9, the part 10a of the laminated section 10 is left at the forming location of the electrode 9 without etching the part 10a and the electrode 9 is formed continuously from the part 10a and the n-type layer 3 exposed around the part 10a. Therefore, the part 9a of the n-side electrode 9 on the part 10a of the laminated section 10 is formed at nearly the same height as that of the p-side electrode 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light emitting diode in which a semiconductor layer is laminated on a substrate to form a light emitting layer, and both p-side and n-side electrodes are provided on the same surface on which the semiconductor layer is laminated. The present invention relates to a semiconductor light emitting device such as a laser diode. More specifically, the present invention relates to a semiconductor light emitting device in which both electrodes are formed at substantially the same height from a substrate.

[0002]

2. Description of the Related Art For example, a light emitting diode (hereinafter, referred to as an LED) of a blue type (from ultraviolet rays to yellow) is shown in FIG.
As shown in a schematic diagram of an example of the ED chip, a gallium nitride-based compound semiconductor layer is formed by lamination on an electrically insulating substrate made of sapphire. That is, an n-type layer (cladding layer) 23 in which, for example, n-type GaN is epitaxially grown on a sapphire substrate 21 and a material whose band gap energy is smaller than that of the cladding layer, for example, an InGaN-based material (the ratio of In to Ga is lower). An active layer 24 made of a compound semiconductor and a p-type layer (cladding layer) 25 made of p-type GaN.
A p-side (upper) electrode 28 is provided via a current diffusion layer made of an -Au alloy layer, and a part of the laminated semiconductor layer is etched and exposed to the n-side (lower) surface of the n-type layer 23. It is formed by providing the electrode 29.

[0003] An LED chip having this structure is die-bonded to the tip of a lead or the like, and two leads and p-side and n-side electrodes are connected by wire bonding such as a gold wire. The LED chip is bonded face down so that the electrodes on the n-side and n-side are connected separately, and the periphery is molded with resin to form a light-emitting element lamp that emits light from the side opposite to the lead. An LED chip is bonded on a substrate provided with terminal electrodes at both ends, and each electrode is used as a chip-type light emitting element in which each electrode is connected to the terminal electrode by wire bonding.

On the other hand, in a mesa stripe type semiconductor laser in which a current injection region is formed in a mesa shape and limited in a stripe shape, and as described above, a semiconductor laser using an electrically insulating substrate is used as shown in FIG. Die bonding is performed face down, and both electrodes 38 and 39 are simultaneously electrically connected to electrode terminals (not shown) of the mount table 41 by a low melting point metal 40 such as cream solder, In, or Au-Sn. In FIG. 5, 31 denotes a sapphire substrate, 33 denotes an n-type cladding layer, 34 denotes an active layer, and 35 denotes a p-type cladding layer.

[0005]

In a semiconductor light emitting device in which a semiconductor layer is laminated on an insulating substrate like the above-mentioned blue semiconductor light emitting device, both the p-side electrode and the n-side electrode are on the same surface side. Often provided. As described above, in a semiconductor light emitting device in which both electrodes are provided on the same surface side, an electrical connection between the two electrodes and a lead or a terminal electrode of a chip type device is made by wire bonding. However, as described above, in a semiconductor light-emitting element in which both electrodes are provided on the same surface side, one electrode is provided on the semiconductor layer above the stacked semiconductor layer, and the other electrode is provided on the semiconductor layer on which the other electrode is stacked. A portion is provided in a lower semiconductor layer which is removed by etching or the like and exposed. Therefore, the height of both electrodes does not become the same height from the surface of the substrate. If the heights of the two electrodes are not the same, bonding cannot be performed at the same pressure between the p-side electrode and the n-side electrode during wire bonding.
For this reason, there is a problem that bonding failure occurs and bonding reliability decreases. On the other hand, if the bonding conditions are changed by both electrodes, the bonding process becomes very complicated.

In the case where the two electrodes are directly bonded to the tips of the leads face down with the LED chip facing down, or when the laser die auto chip is die-bonded face down on a mount base,
If there is a step in the height of the electrode portion of the chip or the laser diode chip, there is a problem that bonding is difficult and the chip is easily inclined. Especially for laser diode chips
When die bonding is performed with a tilt, there is a problem that the beam is tilted and desired characteristics cannot be obtained. Further, the stripe portion left in the mesa shape has a very small width of about several μm, and the force applied to the portion is large, so that the stripe portion is easily deteriorated. In particular, die bonding is performed while scrubbing to remove an oxide film formed on the surface of the low melting point metal during die bonding. However, since a large force is applied to a narrow stripe portion, the stripe portion is easily deteriorated.

The present invention has been made to solve such a problem, and a part of a stacked semiconductor layer is removed by etching or the like, and a p-side electrode and an n-side electrode are formed on the same surface.
It is another object of the present invention to provide a semiconductor light emitting device in which a side electrode is provided, the electrical connection between the electrode and another lead or the like is ensured, and the reliability is improved.

Another object of the present invention is to provide a semiconductor laser in which a mesa stripe portion is not deteriorated or tilted to lower beam characteristics even when a mesa stripe type semiconductor laser is manufactured by die bonding face down. It is to provide a laser.

[0009]

SUMMARY OF THE INVENTION A semiconductor light emitting device according to the present invention comprises a substrate, a semiconductor laminated portion laminated on the substrate to form a light emitting layer, and a first conductivity type on the surface side of the semiconductor laminated portion. A first electrode provided in connection with the first semiconductor layer, and a second electrode provided in connection with a second conductivity type semiconductor layer in which a part of the semiconductor laminated portion is removed by etching and exposed.
And the first and second electrodes are formed so as to have substantially the same height from the substrate.

Here, the substantially same height means that when an LED chip or a laser chip is bonded face down, there is no extreme step between the p-side electrode and the n-side electrode.
It is possible to perform bonding so as not to cause inclination by a normal method, and to perform wire bonding between the p-side electrode and the n-side electrode so that a step does not occur to such an extent that there is no extreme difference in bonding pressure conditions. means. Further, the first conductivity type and the second conductivity type are such that when one of the n-type and p-type of the polarity of the semiconductor is the first conductivity type, the other p-type or n-type is the second conductivity type. Means that.

With this structure, the p-side electrode and the n-side electrode
Even when the LED chip or the laser chip is bonded face down so that the side electrodes are directly bonded to the tip of the lead or the submount, respectively, there is no step, so that the die bonding can be easily performed without inclination. Also, in the case of wire bonding, bonding can be performed to the p-side electrode and the n-side electrode under the same conditions, so that bonding can be performed easily and reliably.

The second electrode is formed continuously with a semiconductor layer of the second conductivity type, which is exposed by removing a part of the semiconductor laminated portion, and a portion where the semiconductor laminated portion remains without being etched. Thereby, the semiconductor device can be reliably electrically connected to the second conductivity type semiconductor layer, and the pad portion of the electrode to be subjected to wire bonding or the like is formed on the stacked semiconductor laminated portion and is the same as the first electrode. Can be height.

The substrate is an electrically insulating substrate,
The effect is particularly large when the semiconductor laminated portion is a gallium nitride compound semiconductor.

The gallium nitride compound semiconductor is a compound of a group III element Ga and a group V element N or
Compounds in which part of the group III element Ga is replaced by another group III element such as Al or In and / or compound in which part of the group V element N is replaced by another group V element such as P or As. Semiconductor.

In the case where the semiconductor laser is formed by mesa etching so that the semiconductor layer of the first conductivity type remains in a stripe shape, there is no deterioration of the stripe portion at the time of bonding and no inclination of the beam. A high-performance semiconductor laser can be obtained.

[0016]

Next, a semiconductor light emitting device of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing a cross section and a plan view of a chip of a semiconductor light emitting device of the present invention in which, for example, a gallium nitride compound semiconductor suitable for blue light emission is laminated.

The semiconductor light emitting device of the present invention is, for example, shown in FIG.
As shown in FIG. 1, a semiconductor layer 3 for forming a light emitting layer on the surface of a substrate 1 made of sapphire (Al ₂ O ₃ single crystal) or the like.
5 are laminated to form a semiconductor laminated portion 10, which is electrically connected to a semiconductor layer (p-type layer 5) of the first conductivity type on the surface side to form a p-side electrode (first electrode) 8. Have been. In addition, the second exposed part of the semiconductor laminated portion 10 is removed.
An n-side electrode (second electrode) 9 is formed electrically connected to the conductive semiconductor layer (n-type layer 3). In the present invention,
The n-side electrode 9 is not provided only on the n-type layer 3 exposed by the etching, but a portion 10a of the semiconductor laminated portion is left without being etched at the place where the n-side electrode 9 is formed, and the remaining semiconductor laminated portion is formed. It is characterized in that an n-side electrode 9 is formed continuously from a portion 10a of the portion and the exposed n-type layer 3 around the portion 10a. As a result, the portion 9a of the n-side electrode on the remaining portion 10a of the semiconductor laminated portion is formed as a connection portion such as wire bonding, so that the portion 9a is formed at substantially the same height as the p-side electrode 8.

That is, in the portion where the n-side electrode 9 is formed, as shown in FIG. 1, a part of the semiconductor lamination portion 10 is etched to expose the n-type layer 3. However, in the present invention, as shown in FIG. 1B, a portion 10a of the semiconductor laminated portion is left at the place where the n-side electrode 9 is formed, and the remaining portions 10a and 10a of the semiconductor laminated portion are formed. An n-side electrode 9 is formed on the surrounding n-type layer 3. At this time, there is a step between the n-type layer 3 and the upper surface of the remaining portion 10a of the semiconductor laminated portion, but there is no problem even if the electrode is cut between them, as long as the electrode is not cut over the entire periphery, and step coverage is a problem. Never be. The n-side electrode 9
Is formed of, for example, an alloy of Ti and Al having good ohmic contact characteristics with the n-type layer 3 as in the prior art. Although the surface of the remaining portion 10a of the semiconductor laminated portion may remain as the p-type layer 5, there is no need to consider the ohmic contact characteristics with the p-type layer 5, and only the ohmic contact with the n-type layer 3 is required. Should be considered.

Further, a part 10 of such a semiconductor laminated portion is formed.
a, the mask is patterned so that the resist film remains only in that portion, and the semiconductor laminated portion 1 is formed.
It is formed by etching 0, and can be formed in the same manner with the same man-hour as etching the semiconductor laminated portion 10 to provide the conventional n-side electrode 9. Further, a part 10a of the remaining semiconductor laminated portion is shown in FIG.
As shown in (1), it is not necessary to provide at the center of the exposed n-type layer 3, but may be provided anywhere as long as the p-side electrode is not short-circuited with the p-type layer 5 to be connected.

The semiconductor laminated portion 10 is made of, for example, a low-temperature buffer layer made of GaN and an n-type GaN and / or AlGaN-based (which means that the ratio of Al to Ga can be variously changed, hereinafter the same) a clad layer. N-type layer 3 having a layered structure of a material having a band gap energy smaller than that of the cladding layer, for example, In
An active layer 4 made of a GaN-based compound semiconductor and a p-type layer (cladding layer) 5 made of a p-type AlGaN-based compound semiconductor layer and / or a GaN layer are sequentially laminated.

The p-side electrode 8 is formed by a laminated structure of Ti and Au via a current diffusion layer made of an alloy layer of Au and Ni (not shown). After the current diffusion layer is formed, n
When the etching for forming the side electrode is performed, a current diffusion layer may be formed on the surface of a portion 10a of the remaining semiconductor laminated portion. Part 10a of remaining semiconductor laminated portion
Is for adjusting the height of the n-side electrode 9.

In order to manufacture this semiconductor light emitting device, for example, a metal organic chemical vapor deposition (MOCVD) method is used.
A reactive gas and a necessary dopant gas are introduced to epitaxially grow the n-type layer 3 about 1 to 5 μm, the active layer 4 about 0.05 to 0.3 μm, and the p-type layer 5 about 0.2 to 1 μm. . Thereafter, Ni and Au are laminated by vacuum deposition or the like, respectively, and alloyed by sintering. A current diffusion layer (not shown) for transmitting light emitted from the active layer 4 and diffusing current is set at 2 to 1.
It is formed to a thickness of about 00 nm. Next, a resist film is provided on the surface, patterned, and the laminated semiconductor laminated portion 10 is partially removed by reactive ion etching using chlorine gas or the like, as shown in FIG. 1B. At the time of this patterning, the resist film is left so that a part 10a of the semiconductor laminated portion remains. Thereafter, the p-side electrode 8 and the n-side electrode 9 are formed by depositing the above-described electrode metal and patterning the same, or by a lift-off method.

According to the present invention, since the p-side electrode 8 and the n-side electrode 9 of the LED chip are formed on substantially the same plane,
For example, as shown in FIG.
3 is die-bonded to the first lead 11, and the p-side electrode 8 and the n-side electrode 9 are respectively connected to the second lead 1.
When performing wire bonding with the second and first leads 11 and the gold wire 14 or the like, since both electrodes 8 and 9 are substantially on the same surface, uniform bonding can be performed even with an automatic wire bonding machine. it can.

Further, as shown in FIG.
The LED chip 13 is also used for bonding such that the electrodes 9 and 8 are electrically connected to the first and second leads 11 and 12 with the D chip 13 facing down.
Since the p-side electrode 8 and the n-side electrode 9 are substantially in the same plane,
Bonding can be performed by mounting the leads 11 and 12 on the same height, and die bonding can be performed easily and reliably. Note that these LED chips 13 are covered with a resin that transmits light emitted by the LED chips 13 to form the resin package 15, thereby forming a lamp-type light emitting element.

On the other hand, in order to make the n-side electrode 9 substantially the same height as the p-side electrode 8, a part 10
Providing a only changes the patterning of the mask when partially etching the semiconductor laminated portion 10 in order to form the conventional n-side electrode, and the manufacturing process does not change at all. Therefore, the man-hour does not increase during the manufacture of the LED chip, but rather the work is easy during the later bonding, the man-hour is reduced as a whole, and the reliability of the bonding is improved.

3 (a) to 3 (c) are views showing a manufacturing process of a semiconductor laser using a gallium nitride compound semiconductor as another embodiment of the semiconductor light emitting device of the present invention.
(D) is an explanatory plan view of the chip. First, LED
As in the case of the chip, the n-type cladding layer 33, the active layer 34, and the p-type layer 35 are laminated on the sapphire substrate 31 with the same composition and the same thickness. Thereafter, annealing is performed to activate the p-type cladding layer 35. Then, Ni and Au are deposited and sintered,
A p-side electrode 38 made of an Au-Ni alloy is formed in a stripe shape by a lift-off method or the like. Then, the p-side electrode 3
8 and a part 30a of the semiconductor laminated portion remain (FIG. 3).
As shown in (b)), a mask is formed, and the stacked semiconductor laminated portions are partially removed by reactive ion etching using chlorine gas or the like. Next, a laser chip is formed by forming an n-side electrode 39 having a laminated structure of an Al-Ti alloy and Au by a lift-off method or the like and dicing.

By performing die bonding of this chip face-down on a mount base such as a submount, accurate die bonding can be performed without tilting or damaging the stripe-shaped mesa portion. When a semiconductor laser is used, FIG.
As shown in the plan view of FIG. 4D, since light is emitted in a beam form from the chip side surface of the active layer 34, there is no need to take out light from the surface side of the stacked semiconductor layers, and the current diffusion layer is formed. Without being provided, the p-side electrode 38 is provided on the entire surface of the p-type clad layer so that electrical contact is sufficiently performed.

In the examples shown in FIGS. 1 to 3, a blue semiconductor light emitting device using a gallium nitride compound semiconductor is used. However, a red or green semiconductor light emitting device using a GaAs or GaP compound semiconductor is used. System semiconductor light emitting device
If the n-side electrode and the n-side electrode are provided on the same surface side, which is the semiconductor layer side on which the layers are stacked, the present invention is similarly applied to facilitate wire bonding and the like. further,
In the example of the LED described above, the active layer 4 is sandwiched between the n-type layer 3 and the p-type layer 5, but the semiconductor has a pn junction structure in which the n-type layer and the p-type layer are directly bonded. The same applies to a light emitting element.

[0029]

According to the present invention, the p-side electrode and the n-side electrode are formed at substantially (substantially) the same height.
Work such as wire bonding becomes easy, and bonding can be performed reliably. As a result, the cost is reduced by reducing the number of steps and the yield during bonding, and the reliability of bonding is improved.

Further, even when the mesa stripe type semiconductor laser is die-bonded face down, a semiconductor laser having high characteristics can be obtained without damaging the stripe portion and without causing inclination or the like.

[Brief description of the drawings]

FIG. 1 shows an LED according to an embodiment of the semiconductor light emitting device of the present invention.
It is explanatory drawing of a chip.

FIG. 2 is an explanatory sectional view when the LED chip of FIG. 1 is mounted on a lead or the like;

FIG. 3 is a diagram showing a manufacturing process of an example of a semiconductor laser which is another embodiment of the semiconductor light emitting device of the present invention.

FIG. 4 is a perspective explanatory view of an example of a conventional LED chip of a semiconductor light emitting device.

FIG. 5 is an explanatory diagram of face-down die bonding of a conventional semiconductor laser.

[Explanation of symbols]

 Reference Signs List 1 substrate 3 n-type layer 5 p-type layer 8 p-side electrode 9 n-side electrode 10 semiconductor laminated portion

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeshi Tsutsui No.21, Saiin Mizozakicho, Ukyo-ku, Kyoto-shi Inside Rohm Co., Ltd. Inventor Atsushi Ichihara 21 Ryozaki-cho, Saiin, Ukyo-ku, Kyoto City Inside ROHM Co., Ltd.

Claims (5)

[Claims] 1. A semiconductor device comprising: a substrate; a semiconductor laminated portion laminated to form a light emitting layer on the substrate; and a first conductive type semiconductor layer provided on a surface side of the semiconductor laminated portion, the first conductive type semiconductor layer being provided on the surface side of the semiconductor laminated portion. An electrode, and a second electrode provided in connection with a semiconductor layer of a second conductivity type in which a part of the semiconductor laminated portion is removed by etching and is exposed, wherein the first and second electrodes are A semiconductor light emitting device formed to be substantially the same height from a substrate. 2. The semiconductor device according to claim 1, wherein the second electrode is formed continuously on a semiconductor layer of the second conductivity type where a part of the semiconductor laminated portion is removed and exposed, and on a portion where the semiconductor laminated portion remains without being etched. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device is formed. 3. The semiconductor light emitting device according to claim 1, wherein said substrate is an electrically insulating substrate. 4. The semiconductor light emitting device according to claim 1, wherein said semiconductor laminated portion is made of a gallium nitride compound semiconductor. 5. The semiconductor light emitting device according to claim 1, wherein the semiconductor laser is formed by mesa etching so that the semiconductor layer of the first conductivity type remains in a stripe shape.